Okay, I'll touch on things as they come to mind.
First off, in regards to killing in the Gravel Pit? It's an underground fight club. If someone is killed, so be it - the event organizers will clean up the mess and dispose of the body. But if it becomes a habit, then the Management may take the time to come and have a chat with the perpetrator. Too much killing is bad for business.
As far as the Resonance goes, I like what Anyr said. I realize the Seraph resonance can be a bit arbitrary in some regards, so I've always just defaulted a bit to the notion of common sense in regards to its resolution. Sorry. I'm all for handing out the Truth for a lot of things, but I don't want major campaign spoilers from Joe-Blow in a dive bar or fight club. If you can snare the spoilers from someone who'd actually know about it, then I'd be more than happy to give that info.
I hope that's not too much of a problem.
As far as the Demons knowing? It's likely that your reputation will grow among the Demons as you dispatch more and more of them. But to actually find out you're an Angel they'd need to see you perform a Song, switch vessels, assume Celestial form, or - perhaps cause a ripple in the Symphony if you did something out of character for Harry. But for the most part, at this point, they'd likely think your some whack-job Soldier whose got a hard-on for finding and smacking down those you perceive as Demons. The fact that you rough Soldiers up as often as Demons may make them think that you can't tell the difference between the two. They'd keep an eye on you, but until you started making moves against the 'Big Players' of the Los Angeles demon community, you'd be a thorn and an annoyance more than a threat.
But Heaven help you if they find out you ARE an Angel.
Shedim can only possess one body. They lose the divine gift of multiplicity. That's what made Legion such a monster. He's the only Shedim to figure out how to do it again - plus he figured out how to possess more bodies than his forces would allow. Hence the name - Legion.
And in the case of Kyriotates, they've still got only one celestial body.
I may get you to pre-roll a few combat rolls and post them here or in an OOC spoiler - just in case. I'm kosher with that.
As for your first point - about the conversation with Colton? I'll answer that IC.